There is a continuing interest in the preparation of synthetic fragrance and flavor compounds and their use in consumer products. There is a demand, in particular, for compounds with odorant properties similar to damascones.
Damascones (alpha, beta, gamma, and delta isomers) are important odorants in the fragrance and flavor industry, contributing unique fruity, green and floral notes with high diffusion. Damascones structurally contain an α,β-unsaturated ketone group, and thus have been flagged as skin sensitizers. The use of damascones in fragrances and flavors is now highly restricted. The need for damascone replacements is a significant one to the industry.
The compounds of the present invention are derivatives of 2,2,6-trimethylcyclohexane-carboxylate. The carbon skeleton of 2,2,6-trimethylcyclohexane-carboxylate derivatives is similar to the carbon skeleton of the damascenes. However, the troublesome α,β-unsaturated ketone group of the damascones is replaced by an ester, anhydride, or acyl carbonate group.
Few esters and other derivatives of 2,2,6-trimethylcyclohexane-carboxylate are known in the literature. The cis methyl ester has been prepared as described in EP920354 and Helv. Chim. Acta. 1973, 2548-2567. The trans methyl ester has been prepared. See J. Am. Chem. Soc. 1942, 385-389. The ethylester has also been described previously in the patent literature. See U.S. Pat. No. 5,288,702. U.S. Pat. No. 4,439,353 discloses fragrant esters of 2,2,5,6-tetramethylcyclohexane carboxylic acid and 6-ethyl-2,2-dimethylcyclohexane carboxylic acid, which have an additional carbon on the cyclohexyl ring moiety as compared to the compounds of the present invention.
The compounds of the presently disclosed subject matter have not been described elsewhere in the literature, with the exception of tert-butyl-2,2,6-trimethylcyclohexane-carboxylate, which is described in JP 2003241366, JP 11029529 and JP 11029528 for uses other than fragrance and/or flavor. In fact, none of the presently disclosed compounds have been described for use as fragrance and/or flavor materials elsewhere in the art. JP 2003241366, JP 11029529 and JP 11029528 disclose tert-butyl-2,2,6-trimethylcyclohexane-carboxylate in racemic form, not in enantioenriched form.
The compounds of the presently disclosed subject matter can be prepared by several synthetic routes. The compounds of the present invention can be prepared from their carboxylic acid precursors by going through an acid chloride intermediate and reacting with the corresponding alcohol or alkyl halide. Shive et al. uses this method to prepare the methyl ester of 2,2,6-trimethylcyclohexane carboxylic acid (J. Am. Chem. Soc. 1942, 385-389).